Re: Unidentified sulid, La Jolla, 20 June

Justyn Stahl

Sorry, yes, by "headlights" I mean marginal coverts. The marginal coverts appeared to be solid white in contrast to the otherwise black back (speckled white) and black upper wing. Unless someone happens to relocate it and/or gets photos I'm happy to let it go.


On Tue, Jun 20, 2017 at 10:31 AM Stan Walens <stan.walens@...> wrote:
By headlights, I assume you mean there was some white on the marginal coverts or perhaps the scapulars.
In my experience, subadult red-footed and blue-footed have completely dark marginal coverts, but masked/Nazca in second cycle and beyond has white scapulars that can look like headlights.
The only N.A. sulid that is black-backed and shows white marginal coverts, which start coming in in second cycle, is Northern gannet. Let’s not go there.

That being said, as the white feathers on masked booby wings start to come in during second cycle, they can appear as headlights.
Take a look at Tom Benson’s photos of the subadult masked-type booby from Orange County last week, which does show white “headlights."

Stan Walens
San Diego

On Jun 20, 2017, at 9:39 AM, Justyn Stahl justyn.stahl@... [SanDiegoRegionBirding] <SanDiegoRegionBirding-noreply@...> wrote:

About 845, in foggy conditions at La Jolla, I picked up a subadult sulid foraging amongst the kayaks. It was black-backed but with speckling (like a piebald Black-vented Shearwater), white headed, and what struck me was the white "headlights" on the forewing. It was a bit distant/foggy to make out bill color but seemingly was not yellow, more grayish. It flew south out of view. I have no pictures, or much confidence in what it was. It's been 45 minutes and it has not returned.

Justyn Stahl

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